A site where a man with far too much interest in beer gets to write about it.

Wednesday, 23 July 2014

Lager yeast has Tibetan origins

The astonishing news that the origins of lager yeast can be traced back to Patagonia has taken another turn, this time to Tibet. An article in Current Biology reports that the Tibetan Plateau is a more likely source of lager yeast's cold tolerant ancestor:

"Lager-brewing arose in 15th century Bavaria and is nowadays the
most popular technique for alcoholic beverage production in the world.
The technique is characterized by low temperature fermentation using the
domesticated yeast Saccharomyces pastorianus (synonym S. carlsbergensis). It has been clear that the lager yeast is a hybrid with one portion of its genome having originated from S. cerevisiae
ale yeast . However, the source of the non-ale subgenome, which
endows lager yeast with cold tolerance, had been a matter of debate
. Recently, a Patagonian origin hypothesis of lager yeast has been
proposed based on the discovery of a new cryotolerant Saccharomyces species from Patagonian native forests of Argentina . This yeast, named S. eubayanus,
exhibited the closest known match (99.56%) to the non-ale portion of
lager yeast and, thus, was believed to be its progenitor. However, we
now show that this yeast species is likely native to the Tibetan
Plateau. One of the Tibetan populations of the species exhibits closer
affinity with lager yeast than the Patagonian population as inferred
from population genetics and genome sequence analyses. We thus provide
strong evidence for a Far East Asian origin hypothesis of lager yeast,
which apparently corresponds better with geography and world trade
history."

I was admit when I first heard the Patagonia news I was more than a little dubious about it. It seemed so unlikely I found it hard to believe, but with strong evidence to back up the claim I had to accept it. Now that it seems that Tibet has an even stronger claim I don't feel quite as surprised. I guess I've only a limited capacity for astonishment. In fact if the next bit of news narrows the source down to a bottle of Tibetan beer a yeti gave to Lobsang Rampa I'll probably just nod along matter-of-factly.